Condensate Drain Pan

ABSTRACT

A condensate drain pan in particular for use in combination with a HVAC system, comprising a sump, an inlet and an outlet for gases, in particular combustion gases, as well as an outlet for condensate. The sump is made of a non-corrodible or corrosion-resistant material, such as a chemically inert-synthetic plastics material, in particular a thermoplastic elastomer, preferably elastic thermoplastic copolyester. The pan may be produced by rotational molding, preferably as one piece. The invention also concerns a HVAC system provided with such condensate drain pan.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a continuation application of the Dutch PatentApplication Serial Number NL2007923, entitled “Condensate Drain Pan”, toJMK Heating B. V., Helmond, the Netherlands, and Kumagaya KunststoffenV.o.f., Holten, the Netherlands, filed on Dec. 5, 2011, and thespecification and claims thereof are incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable.

COPYRIGHT MATERIAL

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a condensate drain pan in particular for use incombination with a HVAC system, comprising a sump, an inlet and anoutlet for gases, in particular combustion gases, as well as an outletfor condensate. The invention further concerns a HVAC system providedwith a condensate drain pan according to the invention.

2. Description of Related Art

A condensate drain pan is for instance applied in HVAC systems (heating,ventilation, air conditioning), in particular in heating systems. Forinstance in a heating system, combustion gases of a boiler flow througha heat-exchanger. Most of the heat of the combustion gases will betransferred to a fluid in the heating system. The combustion gases thenflow through a flue. Combustion gases contain water vapor and combustionproduct gases such as SO² and CO². During cooling of the combustiongases the vapor will condensate. The condensate water will containdissolved gases and is therefore acid. The acid condensate water mayreact with the drain pan and the flue. In time regular inspection isrequired and may result in costly replacement of affected parts.

Such condensate drain pan is for instance described in GB 2.425.588. Thesump of the condensate drain pan is made of a metal suitable forapplication in an acid environment, such as aluminum or stainless steel.Still such sump is vulnerable to acid corrosion, in particular for the,above average acid condensate of the flue. GB 2.425.588 thereforeprovides for a collector device located between the flue and the sump.The collector device is made of non-corrodible or corrosion-resistantmaterial. This known condensate drain pan has several disadvantages. Themain part of the sump, in particular the metal part between the heatexchanger and the flue, is still vulnerable to acid corrosion. Althoughthe condensate of the heat exchanger is less acid than that of the flue,it still provides an acid environment. Therefore also this condensatedrain pan requires regular inspection. It has to be designed such thatinspection is possible, for instance by applying expensive inspectionports in the sump, or by opening the condensate drain pan duringinspection. Opening of the condensate drain pan for inspection andreplacement of the drain pan will in most cases also require replacementof the sealing. Inspection of the condensate drain pan and replacementof affected parts thereof is therefore expensive. Further, thiscondensate drain pan consists out of many parts, which makes itexpensive and vulnerable for failure. Moreover, the several drainageoutlets are vulnerable for obstruction, for instance by calcification oracid disposition. In addition, the design freedom is restricted. Theoutlet of the sump has to be positioned under the flue. The requirementthat the parts of the condensate drain pain should be replaceable,further restricts the freedom of design. For this reason, in general, atleast the sump is releasable attached to the flue and the heatexchanger, while the flue and the heat exchanger are supportedindependent of the sump. The heat exchanger may for instance be placedon a supporting frame.

Further, EP 1 182 408 (A2) recites a heater with an exhaust gas andcondensate collecting bath passing directly through a channel in itsside wall to the exhaust connection. The bath, the channel and theconnection are combined in a one-piece injection-molded connectingcomponent able to be connected by connecting elements to the undersideof the cast heat radiator.

However, the above document does not indicate how an outlet can be madeusing the mold of FIG. 2 thereof. Even further, the mold of FIG. 2 canfrom a practical point of view not lead to a product as indicatedtherein, especially as element 50 is either obstructing the movement ofthe mold, or provided as a detachable element or the like, leading toleakage when molding. In general it is noted that injection molding orblow molding does not provide products having required specifications.As a consequence further processing is required, making the productsexpensive. Also the quality, life time, product strength, etc., are notsufficient. In short, the recitation of the above document cannot be putinto practice.

WO2009003244 (A1) recites a water heater for heating water includingvarious elements. In an example a water heater having a condensate ductto direct condensate into the water for chemically treating the water isrecited.

The document is not considered relevant for the present invention, as itdoes not relate to a condensate drain pan at all; it only relates to acollection base of plastic. The base itself has no further function.

U.S. Pat. No. 5,476,088 (A) recites methods and apparatus for exhaustingflue products and removing condensate from a combustion of air/gasmixtures provide a condensate collecting pan for flue products. That panis provided with an inlet for flue products and condensate, and with anoutlet for flue products spaced from that inlet. That inlet is providedwith a larger cross-section for flue product and condensate flow thanthe outlet. A space is provided in the pan for a flow of flue productsfrom the inlet at a substantially even velocity across the largercross-section of the inlet to the smaller cross-section outlet.Condensate collecting in that space is removed from the pan.

The above document is silent on the material of the pan. Further noexhaust is provided.

WO2009082090 (A1) recites a heat exchanger of an upward combustion typecondensing boiler. The heat exchanger includes a condensed-water traythat discharges condensed water generated from the latent heat exchangeunit. A latent heat exchange unit is installed in such a manner that theflow direction of the exhaust gas passing through the latent heatexchange unit vertically coincides with the falling direction ofcondensed water generated from the latent heat exchange unit.

The above condensate water tray is assembled out of many pieces.

DE 10 2006 026613 A1 recites amongst others a plastic siphon in order toprevent drying up thereof.

Many of the above documents can not relate to a condensate drain panmade of a plastic material, as it is not possible to manufacture such aplastic by molding, specifically by injection molding. Dimensionaltolerance of such molding are in the order of less than 1 mm, such as0.2 mm. However such precise components made of plastic typically have avariation in dimensions of a few mm, such as 2-5 mm, which is fullyunacceptable for the intended purpose. Such is particularly the casewhen parts of plastic need to be attached or combined with otherelements, or need to be melted together, such as for outlets and inlets.Also provision of a mold is typically quite expensive.

The present invention intends to solve one or more of the problems ofthe prior art as described above, and it is in particular an objectiveof the invention to provide a condensate drain pan that is durable inacid environment.

BRIEF SUMMARY OF THE INVENTION

The condensate drain pan according to the invention is characterized byone or several of the appended claims.

In a first aspect of the invention at least the sump is made ofnon-corrodible or corrosion-resistant material. The material used ispreferably also resistant to acids, such as to a pH of less than 5,preferably less than 3, and can withstand high temperatures, such as upto 120° C. Such sump will not corrode, even not in the aggressive acidenvironment of combustion gases and condensate of boilers. Inspection ofthe condensate drain pan is therefore not required and under normalcircumstances the parts of the condensate drain pan need not to bereplaced. Inspection ports may be omitted and more design freedom isobtained. The position of the outlet for condensate and that of theoutlet for combustion gases may be chosen independent of each other.

According to the invention a suitable material may be a chemicallyinert-synthetic plastics material, such as in particular a thermoplasticelastomer, of which category elastic thermoplastic polymer, such as acopolyester proves to be very suitable. In particular polypropylene andpolyphenylene sulphide are suited. These material are not onlynon-corrosive or corrosion resistant, they also provide a goodformability, strength and heat resistance. The choice of a suitedpolymer is not trivial. As mentioned the polymer should be resistant toa relative high and especially a relative low pH, it should be capableof withstanding high temperature, such as above 100° C., and lowtemperature (e.g. during transport −20° C.), it should be capable ofwithstanding expansion and shrinking during temperature variations andtemperature cycles, it should not absorb water. Further many polymerscannot be processed using rotation molding. For not too hightemperatures polypropylene may be used, for even higher temperaturepolyphenylene sulphide is a good candidate. In order to have polymersbeing processed in rotation molding it is preferred to use pellets orgranules, preferably pellets of a suitable size having a relativelynarrow size distribution, e.g. of 1 sigma of 10% relative, preferablyless than 5% relative, even more preferably less than 2% relative. It isnoted that the prior art typically relates to use of a metal, such asstainless steel or aluminum. These metals will however corrode,typically at unexpected locations.

The condensate drain pan may be manufactured by rotational molding.Rotational molding provides very smooth surfaces, which facilitates thecondensate to stream to the outlet for condensate. Even (large)condensate drain pans with a complicated design may be produced in asingle production step. The condensate drain pan may accordingly be onesingle part, avoiding assembly of parts, sealing thereof and edges thateasily get contaminated, the typical places of condensate accumulationand therefore corrosion. The present method provides a condensate drainpan substantially free of stress, having a high durability. The presentmethod also allows for a large variety in shape and size of products.Also the tolerance of e.g. inside dimensions can now be met. Such insidetolerance is in the order of ±0.5% or less, such as ±0.1% (relative). Atypical thickness of the condensate drain pan is 2-20 mm, such as 3-10mm, or 5-8 mm. A thickness of the mold is typically 8-10 mm. The lifetime of the present condensate drain pan is increased dramatically, suchas up to 10 years and longer. The sump may be profiled to furtherfacilitate streaming of condensate toward the outlet opening. Accordingto the invention even the inlets and outlets of gases and condensate mayform an integral part of the sump and may be produced in the singleproduction step. The condensate outlet may be shaped as siphon. Theinvention further provides for the possibility to have an inspectionport as integral part of the sump. Such inspection port may be providedwith a cover. According to the invention one or more of the inlets,outlets, siphon and inspection port may be provided with, internal orexternal, thread.

To a further aspect of the invention the condensate drain pan issuitable for placement on a surface. Such condensate drain surface pandoes not require attachment to for instance a heat exchanger. Thecondensate drain pan may in this respect be provided with legs in orderto obtain free space under the sump for the outlet and/or the siphon. Ina further embodiment of the invention the condensate drain pan has asupport surface to support the HVAC system or a part thereof such as aheat exchanger. A support frame for the HVAC system may therefore beomitted. The condensate drain pan may accordingly be provided withreinforcements.

EXAMPLES

The various aspects of the invention will now be described in moredetail and will be elucidated, by way of example only, with reference tothe accompanying drawing.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The drawings show in

FIG. 1, a heat exchanger of a HVAC system, provided with a state of artcondensate drain pan;

FIG. 2, a schematic cross sectional view of the system of FIG. 1;

FIG. 3, a schematic view of an embodiment of the condensate drain panaccording to the invention;

FIG. 4, a schematic view of another, self-supporting embodiment of thedrain pan according to the invention;

FIG. 5, a heat exchanger of a HVAC system, provided with a condensatedrain pan according the invention and supporting the heat exchanger;

FIG. 6, a mold according to the invention; and

FIG. 7, and in FIG. 8 a condensate drain pan obtained.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 a state of art heat exchanger 1 is shown. The heat exchanger 1has at its upper side a burner with an inlet 4 for gases. Also an inlet2 and an outlet 3 for the liquid of a heating system are provided. Theheat exchanger 1 is placed on a supporting structure 5. Under the heatexchanger 1 a condensate drain pan 6 is provided. The condensate drainpan 6 has an outlet 7. The outlet 7 may be provided with a flue.

The heat exchanger 1 of FIG. 1 is in a schematic cross-sectional viewshown in FIG. 2. In FIG. 2 at the outlet 7 a flue is positioned. Gaseswill enter the heat exchanger 1 at inlet 4 and will be heated by aburner. Fluid of heating systems enters the heat exchanger 1 at inlet 2,flows through the heat exchanger 1 and will exit at outlet 3. In counterflow the flue gases will heat the fluid of the heating systems. The fluegases will flow to the sump 6 and exit the sump 6 at outlet 7. Theoutlet 7 is provided with a flue 8. The flue 8 will guide the combustiongases to the environment.

The combustion gases cool down and expand while cooling down in the heatexchanger 1 and in the flue 8. Combustion gases contain water vapor andcombustion product gases such as SO² and CO². During cooling of thecombustion gases the vapor will condensate. The condensate water willcontain dissolved gases and is therefore acid. The condensate water willbe accumulated in the sump 6 and will leave sump 6 through outlet 12.The acid condensate water may react with the drain pan and the flue. Intime regular inspection is required and may result in costly replacementof affected parts. Accordingly all these parts are replaceable attachedto the heat exchanger. The sump of the state of art condensate drain panis made of a metal suitable for application in an acid environment, suchas aluminum or stainless steel. Still, such sump is vulnerable to acidcorrosion, in particular for the, above average acid condensate of theflue. Therefore, in this prior of art condensate drain pan, a collectordevice 13 is provided and located between the flue and the sump. Thecollector device 13 is made of non-corrodible or corrosion-resistantmaterial. This is an expensive, complicated solution and still is notsatisfying as it does not solve the corrosion problem of the condensatedrain pan in general and as it is still vulnerable for clogging.

FIG. 3 provides a schematic view of an embodiment of the condensatedrain pan according to the invention. The lower part of a heat exchanger35 is placed on a support frame 36. The support frame provides evenbetter dimensional specifications of the product, such as ±0.05%. Underthe heat exchanger 35 a condensate drain pan 30 according to theinvention is provided. The condensate drain pan 30 consists of onepiece. The condensate drain pan 30 consists of a sump 37, an outlet 31for connection with a flue, an outlet 32 with siphon 41 and aninspection port 33, all formed in one single production step. Theoutlets 31, the siphon 41 and the inspection port 33 are provided withthread. On the outlet 31 a flue may be positioned. The outlet 32 withsiphon 41 may be connected to a sewer. On the inspection hole 33 a cover34 is placed. The condensate drain pan 30 is made of a chemicallyinert-synthetic plastics material in particular a thermoplasticelastomer such as elastic thermoplastic copolyester. These materials arealso heat resistant and strong. Moreover they prove to be very suitablefor rotational molding. Rotational molding not only enables productionof the condensate drain pan as one part, it also provides a smoothinternal surface and rounded edges. This will enhance flow of thecondensate to outlet 32. In this respect the sump 37 may have aninternal surface that is profiled, for instance with a sloped bottomwith the lower point at the outlet 32. The outlet 32 of condensate drainpan 30 according to the invention, may be placed at any suitableposition under the sump 37. In general the teachings of the inventionprovide substantial design freedom for the condensate drain pan 30 assuch and for its application in HVAC systems in general. The condensatedrain pan 30 is resistant to corrosion and therefore replacement ofparts due to corrosion will not any longer occur. Although in thisembodiment the pan 30 is provided with an inspection port 33, inspectionfor corrosion is not any longer required. Such inspection port 33 isstill provided to conform present specifications for condensate drainpans. The expectation is however that in time, due to the invention,such requirement will disappear from specification.

The present invention therefore provides a ‘sealed for life’ solution.The embodiment of the invention as shown in FIG. 4 is such sealed forlife condensate drain pan. An inspection port has been omitted. Theupper part of the sump 37 of the condensate drain pan 30 is providedwith inlet 38 for connection with a heat exchanger. The edge of inlet 38is provided with a groove 39. In the groove 39 a sealing may bepositioned. A Quad ring will provide a dynamic sealing between thecondensate drain pan and a heat exchanger. The condensate drain pan 30is provided with legs 40 and may accordingly be self-supporting placedon a surface. As the condensate drain pan 30 according to the inventionis very strong, which strength may be further increased by applyingsuitable reinforcements, the condensate drain pan 30 may even supportthe heat exchanger. Accordingly the support frame 36 as shown in theembodiment of FIG. 3 may even be omitted. In FIG. 5 such combination isshown. The condensate drain pan 30 is provided with legs 40 and placedon a surface. On the condensate drain pan 30 the heat exchanger 1 ispositioned. The condensate drain pan 30 is sufficiently strong tosupport the heat exchanger 1 and as the combination is sealed for lifethe combination will be connected during life time of the heatingsystem.

In FIG. 6 a multi (three) -piece mold is shown. A left part 61 a, aright part 61 b and a top part 64 forming a condensate pan 61. Furtherthe mold is provided with bars 62 to make a support 36. In principle thevarious pieces may be further sub-divided into extra pieces. The mold ispreferably made from aluminum.

In FIG. 7 a condensate drain pan 71 obtained by the mold of FIG. 6,further having sealing rings for exhaust gas 76, 77, bars 82 and anoutlet 75 are shown.

In FIG. 8 a condensate drain pan 81 obtained by the mold of FIG. 6,further having sealing rings 84 for sealing between the condense drainpan and heat exchanger 85 gas 76 and 77, are shown.

To the person skilled in art it is obvious that the above givenembodiments represent only a few of the many possible variations inwhich the condensate drain pan according to the invention may beembodied. Therefore the embodiments given here must be understood as anelucidation to the appended claims without limiting the scope of theinvention. Within the protective scope numerous variations areconceivable. For instance rotation molding also provides the possibilityto apply inserts, for instance threaded insert for connection of thecondensate drain pan with a heat exchanger.

What is claimed is:
 1. A single part condensate drain pan for use incombination with a HVAC system, comprising a sump, an inlet, an outletfor combustion gases, as well as an outlet for condensate, and whereinat least the sump is made of a non-corrodible or corrosion-resistantmaterial.
 2. A condensate drain pan according to claim 1, wherein thesump is of a chemically inert-synthetic plastics material.
 3. Acondensate drain pan according to claim 1, wherein the plastic materialis an elastic thermoplastic polymer.
 4. A condensate drain pan accordingto claim 1, wherein the sump is manufactured by rotational molding.
 5. Acondensate drain pan according to claim 1, wherein one or more of theinlet for gases, the outlet for gases, the outlet for condensate and asiphon form an integral part of the sump.
 6. A condensate drain panaccording to claim 1, wherein the sump is provided with an inspectionport.
 7. A condensate drain pan according to claim 6, wherein one ormore of the inlets, outlets, siphon and inspection ports is providedwith thread.
 8. A condensate drain pan according to claim 6, wherein theinspection port is provided with a cover.
 9. A condensate drain panaccording to claim 1, wherein the sump has a profiled internal bottom.10. A condensate drain pan according to claim 1, wherein the condensatedrain pan is suitable for placement on a surface.
 11. A condensate drainpan according to claim 10, wherein the condensate drain pan has asupport surface to support the HVAC system or a part thereof.
 12. Acondensate drain pan according to claim 10, wherein the condensate drainpan is provided with reinforcements.
 13. An HVAC system provided with acondensate drain pan according to claim
 1. 14. A multi-piece mold formanufacturing a condensate drain pain comprising a left portion, a rightportion, wherein the left and right portion provide an outlet, a sump,and an outlet, and a top portion providing an inlet.
 15. A method ofproducing a condensate drain pan according to claim 1, comprising thesteps of providing a three or four part mold, combining the mold,providing a thermoplastic elastomer, and forming the condensate drainpain by rotational molding.
 16. The condensate drain pan according toclaim 2, wherein the plastics material is a thermoplastic elastomer. 17.The condensate drain pan according to claim 3, wherein the plasticsmaterial is a copolyester.
 18. The condensate drain pan according toclaim 17, wherein the copolyester is one or both of polypropylenecopolymer and polyphenylene sulphide.
 19. The condensate drain panaccording to claim 10, wherein the condensate drain pan is provided withlegs.
 20. The method of claim 15, wherein the thermoplastic elastomer isan elastic thermoplastic copolyester.
 21. The method of claim 20 whereinthe copolyester is one or both of polypropylene copolymer andpolyphenylene sulphide.